Davide Allegrini

Structure|[ndash]|function relationship in early diabetic retinopathy: a spatial correlation analysis with OCT and microperimetry

PurposeTo study the correlation of the local ganglion cell layer—inner plexiform layer (GCL-IPL) thickness with corresponding retinal sensitivity as studied with microperimetry in patients with Type 2 diabetes and no signs of diabetic retinopathy.Patients and methodsWe analyzed 35 healthy subjects (68 eyes) and 26 Type 2 diabetic patients (48 eyes) with no signs of diabetic retinopathy. We tested best corrected visual acuity (BCVA), monocular and binocular constrast sensitivity (CS, Pelli – Robson chart) and retinal sensitivity with microperimetry, and acquired dense macular SD-OCT scans. We then studied the correlation between local GCL-IPL thickness and local sensitivity.ResultsMean BCVA was 1.09 (±1.03) decimals in diabetic subjects and 1.02 (±0.15) decimals in healthy subjects. Only binocular CS was significantly higher in healthy subjects (1.18±0.42 for healthy subjects, 1.62±0.63 for diabetic subjects). In both local and global analysis we observed higher GCL-IPL thickness and higher sensitivity in normal compared with diabetic subjects, but no difference reached significance (p<0.05). Using a mixed multivariate linear model, we found a significant correlation between retinal sensitivity and the correspondent GCL-IPL thickness in diabetic subjects (0.022±0.006 dB/μm, p=0.0007) but not in healthy subjects (−0.002±0.006 dB/μm, p=0.77).Conclusiondespite close similarities between the two groups, we found a significant difference in the structure–function relationship in diabetic subjects without diabetic retinopathy, suggesting that diabetes might act as an additional effect in the normal deterioration of the visual function related to the inner retina.

Optical Coherence Tomography Angiography in a Normal Iris.

BACKGROUND AND OBJECTIVE Optical coherence tomography angiography (OCTA) is a new imaging technique for examining the macular region in many retinal diseases. The aim of this study was to assess the applicability of OCTA to detect iris vascularization. PATIENTS AND METHODS The irises of 28 eyes of 14 patients were examined with AngioVue OCT (Optovue, Fremont, CA). The usual technique was modified using the AngioRetina mode, but with the anterior segment optical adaptor lens, and without autofocus, while making manual adjustments. OCTA scans were captured in both eyes, always by the same operator. The images were acquired in 3 × 3 and 6 × 6 volume cubes. Raw data were then exported and split using an external tool provided by Optovue to obtain three-dimensional (3-D) iris reconstruction. RESULTS In all eyes, OCTA showed the arterial system more superficially and the venous system more deeply in 3-D reconstruction. CONCLUSION This is the first report of a study of the vascularization and 3-D reconstruction of the normal iris with OCTA. The method detects iris vascular network and indirectly provides information on the retinal circulation in situations where this is not visible without injecting sodium fluorescein. [Ophthalmic Surg Lasers Imaging Retina. 2016;47:1138-1142.].

Optical Coherence Tomography Angiography of Iris Nevus: A Case Report.

Iris nevus is common: 6% of patients with suspected iris melanoma have lesions other than melanoma, and 36% of them are nevi. Iris nevus turns into melanoma in approximately 8% of cases at a mean of 15 years. This case report provides the first description of an iris tumor examined with iris optical coherence tomography angiography (OCTA) compared to iris fluorescein angiography (IFA). A 60-year-old man with a diagnosis of iris nevus in the left eye was referred to our department for IFA and iris OCTA. The iris vasculature in IFA was visible only in the early phases, but not clearly. OCTA, however, gave visualization of the vascular network and very precisely defined the vessels of the whole lesion, except for the pupillary portion, which was masked by superficial pigment accumulations. IFA and iris OCTA can add information about the vascular architecture compared to slit-lamp biomicroscopy, ultrasound biomicroscopy, and anterior-segment OCT. However, IFA is time-consuming and invasive and can – very occasionally – cause serious adverse reactions. In contrast, OCTA defines the texture of the iris vasculature better. In conclusion, OCTA is a new method, easy to execute, needing no dye injection, and provides useful information on the vascular network of iris lesions. It could therefore be helpful in the diagnosis and follow-up of these lesions.

Screening of PAX6 gene in Italian congenital aniridia patients revealed four novel mutations

ABSTRACT Purpose: To uncover underlying mutations in a cohort of Italian patients with aniridia, a rare congenital panocular condition with an incidence ranging from 1:64,000 to 1:100,000. The disease may be found isolated or in association with other syndromes characterized by partial or complete absence of the iris and iris hypoplasia. Methods: We analyzed the PAX6 gene in 11 patients with aniridia fulfilling the following inclusion criteria: partial or complete absence of the iris and age < 18 years at the time of diagnosis. DNA sequence analysis was integrated with Multiple Ligation Probe Assay (MLPA) analysis. Results: We identified seven PAX6 mutations, including four novel ones. The majority of mutations lie in the DNA-binding domain and all produce a truncated protein. All tested patients did not have WT1 gene deletions thus excluding the WAGR syndrome. We present the clinical findings in the four cases harboring novel mutations. We were unable to identify mutations in four cases with complete aniridia thus indicating that other gene/s could be involved in the disease. Conclusions: It is important to establish the molecular diagnosis early to avoid repeated and long-term screening for Wilms tumor. Our work further emphasizes that a wide range of ocular phenotypes are associated with loss of function PAX6 mutations. In addition to the possibility of stochastic variations, other genetic variations could play a role as modifier genes, thus giving rise to the observed different ocular phenotypes.

Effect of prophylactic timolol 0.1% gel on intraocular pressure after an intravitreal injection of ranibizumab: a randomized study.

Purpose The purpose of this study is to make a prospective evaluation of the effect of timolol 0.1% eye gel on short-term intraocular pressure (IOP) after an intravitreal injection (IVI) of ranibizumab. Participants and methods One hundred and fifty eyes of 150 IVI-naïve patients with macular edema caused by various pathological conditions (age-related macular degeneration, central or branch retinal vein occlusion, and diabetic retinopathy) were scheduled to undergo an IVI of ranibizumab (0.5 mg/0.05 cc). The patients were randomly divided into three groups: 50 were not treated with timolol before the IVI (group 1); 50 received an instillation of timolol 0.1% eye gel the evening before the IVI (group 2); and 50 received an instillation of timolol 0.1% eye gel 2 hours before the IVI (group 3). The incidence of clinically significant intraocular hypertensive spikes (>25 mmHg and >40 mmHg) was then assessed. Results Our findings showed that mean IOP at baseline was significantly higher than at both 5 and 60 minutes after IVI (P<0.01). Spikes of >25 mmHg were recorded at either time in 27 patients (54%) in group 1, 23 patients (44%) in group 2, and 24 patients (48%) in group 3. None of the between-group differences were significant. Spikes of >40 mmHg (which were only detected 5 minutes after IVI) were recorded in nine (18%), eight (16%), and one patient (2%) in groups 1, 2, and 3, respectively. The only significant difference was between the control and group 3 (P=0.012). Conclusion An increase in IOP after antivascular endothelial growth factor IVI is a frequent complication. The prophylactic use of timolol 0.1% gel effectively reduced the mean IOP when administered 2 hours before IVI and was also effective in preventing dangerous IOP spikes of >40 mmHg. It is therefore recommended before IVIs as a means of preventing emergency procedures and preserving the health of the optic nerve.

Lens opacities in glycogenoses type I and III

OBJECTIVE The glycogen storage diseases (GSD) or glycogenoses comprise several inherited diseases caused by abnormalities of the enzymes that regulate the synthesis or degradation of glycogen. This report presents lens opacities not previously described in patients with type I or III GSD. PARTICIPANTS Eleven patients with type I and III GSD. METHODS We examined a series of 11 consecutive patients (aged 13-40 years) with type I and III GSD by full ophthalmologic examination. RESULTS We found changes of the lens on 7 of 11 patients (aged 23-40 years) with glycogenoses I and III. In 6 patients, the lens showed multiple, bilateral, punctate, and peripheral opacities; only 1 patient showed a posterior subcapsular opacity in both eyes. We did not observe changes in the cornea and the posterior pole correlated to the accumulation of glycogen and lipids. CONCLUSIONS In this series, we found that 60% of patients with type I and III GSD show lens opacities. These opacities are bilateral, peripheral, multiple, and small; they do not give any visual disturbance. Considering that subjects with age ranging from 13 to 23 years had no lens opacities, we postulate that they could progressively develop over time because of exposure to recurrent attacks of hypoglycemia, which lead to a progressive depletion of hexokinase.

Features of the normal choriocapillaris with OCT-angiography: Density estimation and textural properties

The main objective of our work is to perform an in depth analysis of the structural features of normal choriocapillaris imaged with OCT Angiography. Specifically, we provide an optimal radius for a circular Region of Interest (ROI) to obtain a stable estimate of the subfoveal choriocapillaris density and characterize its textural properties using Markov Random Fields. On each binarized image of the choriocapillaris OCT Angiography we performed simulated measurements of the subfoveal choriocapillaris densities with circular Regions of Interest (ROIs) of different radii and with small random displacements from the center of the Foveal Avascular Zone (FAZ). We then calculated the variability of the density measure with different ROI radii. We then characterized the textural features of choriocapillaris binary images by estimating the parameters of an Ising model. For each image we calculated the Optimal Radius (OR) as the minimum ROI radius required to obtain a standard deviation in the simulation below 0.01. The density measured with the individual OR was 0.52 ± 0.07 (mean ± STD). Similar density values (0.51 ± 0.07) were obtained using a fixed ROI radius of 450 μm. The Ising model yielded two parameter estimates (β = 0.34 ± 0.03; γ = 0.003 ± 0.012; mean ± STD), characterizing pixel clustering and white pixel density respectively. Using the estimated parameters to synthetize new random textures via simulation we obtained a good reproduction of the original choriocapillaris structural features and density. In conclusion, we developed an extensive characterization of the normal subfoveal choriocapillaris that might be used for flow analysis and applied to the investigation pathological alterations.

Transient Esotropia in the Child: Case Report and Review of the Literature

The aim of this report is to investigate the possible causes of acute acquired onset of transient esotropia (AATE) in children and to help to differentiate ophthalmoplegic migraine (OM) from accommodative spasm (AS). A case of an 8-year-old Caucasian female affected by AATE and diplopia is described. The day before AATE onset, the patient complained of slight headache without nausea and vomiting, with spontaneous resolution. AATE diagnosis is challenging. The most likely ophthalmological causes of AATE are AS and OM. In these cases it is important to evaluate the presence of both a familial history of recurrent headaches and an AATE associated with migraine, ptosis, nausea, and vomiting. A full ophthalmological evaluation and a thorough refractive examination in cycloplegia are mandatory to exclude ophthalmological causes.

Grisel’s syndrome, a rare cause of anomalous head posture in children: a case report

BackgroundAnomalous head posture (AHP) or torticollis is a relatively common condition in children. Torticollis is not a diagnosis, but it is a sign of underlying disease. Grisel’s syndrome (GS) is a rare condition of uncertain etiology characterized by a nontraumatic atlanto-axial subluxation (AAS), secondary to an infection in the head and neck region. It has not been considered, in ophthalmological papers, as a possible cause of AHP.Case presentationA case of AAS secondary to an otitis media is studied. The children showed neck pain, head tilt, and reduction in neck mobility. The patient had complete remission with antibiotic and anti-inflammatory therapy and muscle relaxants. Signs of GS should always be taken into account during ophthalmological examination (recent history of upper airway infections and/or head and neck surgeries associated to a new onset of sudden, painful AHP with normal ocular exam). In such cases it is necessary to require quick execution of radiological examinations (computer tomography and/or nuclear magnetic resonance), which are essential to confirm the diagnosis.ConclusionGS is a multidisciplinary disease. We underline the importance of an accurate orthoptic and ophthalmological examination. Indeed, early detection and diagnosis are fundamental to achieve proper management, avoid neurological complications and lead to a good prognosis.

The Paediatric Patient: Identifying Congenital Aniridia as Soon as Possible

Aniridia is a congenital panocular condition affecting iris, cornea, anterior chamber angle, lens, retina and optic nerve. It is rare but it can progressively impair vision in multiple causes including keratopathy, cataract, glaucoma, foveal hypoplasia, nystagmus. Aniridia is a genetic haplo-insufficiency expression of the PAX6 gene located on the chromosome 11p13. Aniridia, genital anomalies, retardation and Wilms tumor are called WAGR Syndrome. In this chapter we emphasize the importance of a thorough ophthalmologic evaluation of the anterior and posterior segment, and orthoptic for the evaluation of strabismus, nystagmus and ocular motility. The assessment of visual acuity for distance and near must take into account the age of the patient, in order to use more appropriate methods. There are various forms, w hich are different for clinical manifestations and visual acuity. It is important an early diagnosis and an early treatment of complications, to save visual ability and the visual field, in order to reduce the damage and to maintain a better quality of life in aniridic patients.